1. Field of the Invention
The present invention relates generally to printing press reservoirs and, more specifically, to a gravity feed fountain solution supply apparatus for supplying a temperature controlled fountain solution to the fountain solution pan of a printing press.
2. Description of the Related Art
Fountain solutions were historically gravity fed from the fountain solution tank to the fountain solution pan of a printing press. Gravity fed systems have the advantage of design simplicity and near zero waste of fountain solution. As the art of lithography developed, it was discovered that controlling the temperature of the fountain solution led to greater and more consistent quality of print. In order to maintain consistent temperatures within the fountain solution, refrigerated fountain solution recirculating systems were developed. These recirculating systems also incorporated an apparatus for adding an accurate amount of alcohol to the fountain solution, to use as a wetting agent, i.e., to reduce the surface tension of the fountain solution. This development worked well for years mainly because the alcohol helps to mask or to reduce the effects of the contaminants. However, it was discovered that the alcohol in the fountain solution poses a serious health risk to the operators of printing presses. Therefore, elimination of alcohol as a wetting agent had become a priority in the printing industry, and mandatory in some states. As a replacement, wetting agents (i.e., to replace alcohol) were developed, the effects of the contaminants became a disproportionate problem. With recirculating systems, contamination to the fountain solution accrues while the solution circulates and recirculates through the system. Specifically, plasticizers from the rollers, and paper particles and spray powder from the sheets migrate into the fountain solution. Thus, the fountain solution typically has to be changed every few days, which, can be an expensive waste disposal problem. Another problem with recirculating systems is excessive use of water and other resources, and loss of time, that is, approximately two hours down time every few days while the contaminated fountain solution is being changed. Again, the advantage of the recirculating system is that it is easier to cool because the fluid is circulating. Thus, there is a need for a fountain solution supply system which solves the above problems. More precisely, there has been a need for a temperature controlled, gravity feed fountain solution supply system which has an efficient method for maintaining a cool fountain solution temperature, particularly with the larger offset presses that produce substantial heat. The related art discussed below is representative of developments prior to my invention.
U.S. Pat. No. 4,146,474 issued to Kagatani on Mar. 27, 1979 describes a method and apparatus for controlling dampening water in printing machines. Kagatani is a recirculating unit rather than a gravity feed unit. Kagatani therefore does not teach the present invention as claimed.
U.S. Pat. No. 5,370,046 issued to Spiegel et al. on Dec. 6, 1994 describes an inking unit for printing presses. The device monitors the temperature of rollers by putting a temperature probe in the ink train. This invention pertains to the temperature of ink wells and the ink train, but does not control the temperature in the fountain solution pan. Spiegel et al. therefore do not teach the present invention as claimed.
U.S. Pat. No. 5,720,221 issued to Harig et al. on Feb. 24, 1998 describes an assembly for controlling the temperature of a fountain solution. However, Harig et al. is a recirculating, rather than a gravity feed system and therefore, does not teach the present invention as claimed.
U.S. Pat. No. 5,974,817 issued to Prummer, M. on Nov. 2, 1999 describes an assembly for controlling the temperature of a fountain fluid by pumping it through a printing roller via a heat exchanger, or radiator, located between a recirculating system and the fountain solution pan. Prummer does not teach the present invention as claimed.
Other printing press fountain solution supply systems of general interest are shown in U.S. Pat. No. 5,622,620 issued to Meenan et al. on Apr. 22, 1997, and U.S. Pat. No. 5,749,295, issued to Kurz, H. on May 12, 1998. None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.
The present invention is used to gravity feed a continuous supply of cooled fountain solution for consumption by the printing unit of a commercial printing press. The apparatus uses a refrigerant supplied from a refrigeration unit in one embodiment and chilled water supplied from a chiller in another embodiment. The apparatus includes an insulated, airtight fountain solution supply tank connected to a fountain solution pan via a gravity fed supply tube.
In a gravity feed apparatus, a printing unit continuously consumes fountain solution as the pan roller rotates and consumes fountain solution. The pan is resupplied by operating a valve allowing solution to flow from the tank. The present tank is an insulated, air tight container. An essential feature of the tank is its cooling coils arranged in M-shaped layers. Each of the layers is supported by a perforated, heat-conducting cooling plate for efficient movement of the cooled fountain solution through the tank. A tank thermostat is connected to the refrigeration unit, and to first temperature probe to monitor the tank fountain solution temperature.
An insulated supply tube connects the tank to a fountain solution pan supply pool which is also part of the invention. The supply pool serves as a temporary receptacle for fountain solution traveling from the tank via the supply tube. The pan""s supply pool empties into an elongated dispersement tube that has a plurality of openings that increase in diameter from the near wall to the far wall of the pan. The tube also includes at least three cooling fins extending the length of the dispersement tube.
As the pan roller spins on its axis, fountain solution is consumed from the pan, and thereby drawn by gravity from the tank longitudinally through the dispersement tube and through its openings. From there, the fountain solution circulates around the cooling fins which exchange heat with the dispersement tube and keep the solution in the pan a constant cool temperature.
In another embodiment, cooling coils are also present in the fountain solution pan and there is a separate temperature control for maintaining a desired pan temperature by regulating the flow of coolant to the pan. The pan has a dispersement tube, as above, but, each opening opens into a separate, compartment which is open at both the front, near the pan wall and dispersement tube, and the back, directing the solution to the cooling coil and then to the pan roller.
Accordingly, it is a principal object of the invention to minimize waste solution in a printing press apparatus while maintaining optimally cool temperatures in the fountain solution tank and the fountain solution pan.
It is another object of the invention to minimize contamination in the fountain solution pan.
It is a further object of the invention to minimize the loss of heat energy in a gravity fed fountain solution pan, and to reduce the down time of the printing apparatus.
It is yet another object of the invention to minimize the use of water and other resources in the printing process.
It is an object of the invention to provide improved elements and arrangements thereof in an apparatus for the purposes described which is inexpensive, dependable and fully effective in accomplishing its intended purposes.
These and other objects of the present invention will become readily apparent upon further review of the following specification and drawings.